Critics have been having fun with President Donald Trump’s strange remark that “Our country is full.” They’ve taunted him over everything from population density to the declining birthrate. But Trump has shown little evidence of being swayed by criticism. I therefore have another suggestion: The president should read a comic book.


The book is called “Open Borders: The Science and Ethics of Immigration,” in which the economist Bryan Caplan and the cartoonist Zach Weinersmith take us on a delightful tour of the arguments and evidence behind the debate flagged in the title. (The book won’t be out until the fall, but the publisher kindly sent me an advance copy, and I’m sure would be happy to supply one to the White House, too.)

Before getting into why the volume might be helpful, let me say a word about the title. A lot of libertarians and liberals have adopted the phrase “Open Borders,” but I’m with those who consider the term a political mistake. The vision it conjures is of no border stations, no one keeping track of who’s in what country at what time. That’s not at all what supporters of the idea have in mind, and it’s certainly not what Caplan and Weinersmith have in mind. Borders would still be patrolled, immigrants would still have to fill out forms and so forth. The difference is that there would be few or no restrictions on who could cross.

OK. Preliminaries over. What’s the argument? In the comic, Caplan’s avatar leads us through several, the most important of which is that open borders would lead to an enormous increase in wealth. He credits models suggesting that a policy of open borders might double worldwide GDP, from $75 trillion to $150 trillion — and reminds us that even if the change is smaller than that, it’s still likely to be enormous.

This is where the fun part comes in. “Imagine a million people in Antarctica, farming in the snow,” Caplan says, with matching Weinersmith illustrations. Suppose they were to move to a more fertile country? “The Antarctican immigrants are obviously better off, but they’re not the only beneficiaries.” Why not? Because “In their new country, farmers grow vastly more food” — which they sell, benefiting “everyone who eats.” Letting them in, he writes, would be both the decent and the smart thing to do.

Caplan goes on to provide both arguments and evidence for the proposition that even low-skilled migrants increase the income of those who are already citizens as well as those who have come in search of better lives, and rejects one common counterargument as “the arithmetic fallacy.” Suppose you come across a study that shows that large-scale immigration would reduce average income. Say that “native” families earn an average of $50,000 and foreigners earn an average of $5,000. Open borders, he says, might reduce the average to $40,000 — and yet both sides would be better off. Natives might earn $60,000 and immigrants $20,000 and — well, you see the point.

The book also deals with a number of other arguments in favor of restricting immigration. For instance, Caplan rejects Milton Friedman’s argument that you can’t have both free immigration and a welfare state. He has good answers to claims that immigrants are more likely to commit crimes and that they do not assimilate.

He also considers arguments about how immigration changes culture, and here no doubt Trump would quibble. Caplan doesn’t deny that culture may change, but he presents a view of culture as something more than a museum-like reverence for the past.

What’s refreshing about the way that Caplan responds to the likely criticisms of his thesis is that he’s thoughtful and generous. Nobody is accused or racism or some other less-than-pure motivation. He is not afraid to admit when those who have a different view make a good point. This alone distinguishes this effort from so much of what passes for argument on this issue.

He also concedes that compromise might be necessary. But he argues that if the public has legitimate concerns, “keyhole solutions” — in effect, small incisions — are better than an outright ban. The simplest of these is that if there is fear is about criminal immigrants, then a country could refuse to admit criminals. (See why borders are still necessary?) If there is fear that immigrants will be a drain on social services, then impose a waiting period. And so forth. To those who believe that such rules are hurtful to immigrants, Caplan responds that they’re right — but immigration with strings attached is still better than broad bans. And as he notes toward the end, most of these keyhole solutions are already more or less in place.

The book isn’t perfect, and the careful reader will have questions about a lot of the details. A lot of readers won’t be persuaded. But by presenting the argument in the bright, attractive format of a comic, with characters and cute dialogue to illustrate most of the points, Caplan has made a contribution that even a skeptical president should love.


Stephen L. Carter is a Bloomberg Opinion columnist. He is a professor of law at Yale University and was a clerk to U.S. Supreme Court Justice Thurgood Marshall. His novels include “The Emperor of Ocean Park,” and his latest nonfiction book is “Invisible: The Forgotten Story of the Black Woman Lawyer Who Took Down America’s Most Powerful Mobster.”